Shortly before this morning's blast, New York utility Con Edison received a call about a possible gas leak from an apartment building nearby, a Con Edison official told CNN. A utility truck was dispatched but the explosion happened before it arrived, the official said.

CNN's John Berman says an odor was reported at 9:13 a.m. from 1652 Park Avenue, just a few doors from 1644 and 1646 Park Avenue.

CNN iReporti was actually right on the next building while i heard a huge explosion inside my apartment i thought the Metro North derailed, the whole building just shaken for a moment. i ran downstairs and took ...

by Dorrine Mendoza3/12/2014 3:46:32 PM

Mayor arrives

New York City Mayor Bill de Blasio is now at the scene of the disaster.

We hear NYPD commissioner William Bratton is on his way as well.

by Rachel Clarke3/12/2014 3:48:55 PM

Details from gas company

Con Edison, the local power company, is tweeting out what happened when.

It says a call of a gas odor came in at 9:13 a.m. and a crew was sent out two minutes later. That crew got there just after the explosion at 9:40 a.m.

A second person has died as a result of the Harlem building collapse, a New York Police Department officer told CNN. Both of the dead are female, according to the officer. An earlier report said a man had been killed.

The names of the women have not been released.

by Rachel Clarke3/12/2014 3:59:28 PM

More fire crews

There are now more than 250 firefighters working to tackle the blaze and search for victims.